chore: add synth metadata file (#2924)
chore: add synth metadata file (#2924)


chingor13/google-cloud-php,googleapis/google-cloud-php,chingor13/google-cloud-php,chingor13/google-cloud-php,googleapis/google-cloud-php,googleapis/google-cloud-php,jdpedrie/google-cloud-php,jdpedrie/google-cloud-php,jdpedrie/google-cloud-php